Until some farmers in County Antrim noticed two giant US Galaxy aircraft touching down at RAF Aldergrove outside Belfast, no one in Northern Ireland - outside government circles - had a clue that they were about to play host to the US president.

Politicians had been gearing up instead for a joint visit by the British and Irish prime ministers, who are due to unveil their proposals to break the deadlock in the NI peace process later this week.

But the president's intervention will serve to kill a number of birds with the same stone.

No one who witnessed the low key nature of this year's Presidential St Patrick's day celebrations in Washington will be under any illusions that George W Bush is immersed in the detail of the NI peace process.

Dynamics

However Downing St believes it will increase the pressure on the key players in the process to agree to move forward on the basis of the British and Irish proposals if the president publicly endorses them and calls for so called acts of completion on all sides.

POLICING AND PEACE

On the issue seen as crucial to Sinn Fein's participation - the transfer of policing and justice powers to local politicians - there appears to be deadlock

For both Tony Blair and George W Bush, the main item on the agenda will undoubtedly be the war in Iraq.

But at a time when some are accusing the president and the prime minister of being warmongers, it is obviously helpful for both leaders to stress their support for peace in a very different context.

Downing St has called for help from the White House before - most notably when President Clinton put in late night phone calls to the NI parties at crucial stages during the negotiations that led to the Good Friday Agreement (GFA).

The dynamics of this visit maybe some what different.

Embarrassed

Whilst anti-agreement politicians, such as the DUP, will no doubt be annoyed they are not being granted a meeting with the president, both the main nationalist parties SDLP and Sinn Fein could be a little embarrassed by taking part in the summit during a war which they have both denounced.

The Irish Prime Minister, Bertie Ahern, will also travel north to meet President Bush.

His government remain officially neutral on the war, but he has withstood pressure from anti-war campaigners to halt US military overflights and landing arrangements at Shannon Airport in the west of Ireland.

Once the president has gone Mr Blair and Mr Ahern are expected to return to NI to push ahead with their joint initiative probably on 10 April, which is the fifth anniversary of the GFA.

Everything hangs on a generous response to their proposals from both the IRA and the Ulster Unionist party, and the governments will hope that in giving this week an added sense of occasion the President's visit will make that response more likely.